State of the art powdered, solid, liquid and unitized dose (tablet, pouch and sheet) detergents have several limitations. One limitation is that fragrance delivery to the fabrics through the wash is limited. The only practical method to obtain heavily scented clothing is to use several heavily scented dryer sheets in the clothes dryer at one time. Detergents that deliver fragrance to the wash liquor do not deliver fragrance that is substantive enough to make it through the rinse water and onto the wet fabrics transferred into the clothes dryer. A significant portion of the fragrance contained in the detergent does not adsorb onto the fabrics and instead is drained away and wasted in the washing machine.
Consequently, in order to achieve high fragrance retention on the fabrics, a second product is added during either the rinse cycle of the washing process (a heavily scented liquid fabric softener for example), or more preferred, added directly to the dryer in the form of a fabric softener sheet (a dryer sheet).
A second limitation of these conventional detergent and conditioning products is that it is difficult for a detergent to deliver either an anti-static benefit or a softening benefit due to the incompatibility of the quaternary ammonium compounds, the chemical required for either of these benefits, and the anionic surfactants that are required in detergent compositions for good cleaning. While a number of recent new product introductions have claimed to deliver “2-in-1” detergent benefits (cleaning+anti-stat/softening), the level of conditioning performance achieved by these products has been so very low so as to not be perceivable by the consumer.
WO 07/120,867 A2 discloses a laundry article that overcomes the above mentioned drawbacks and that comprises a water-insoluble substrate coated with detergent, fabric conditioning, and optionally other fabric treatment compositions, which functions as a single product for washing and conditioning fabrics when added to the washing machine and then carried along with the wet clothes into the clothes dryer. The laundry article comprises a water-insoluble substrate onto which a minimum of two compositions is applied in “zones”.
The fabric conditioning composition applied to the substrate includes a quaternary ammonium cationic surfactant, such as traditional tetraalkyl materials or ester quaternaries. These materials are waxy solids or are highly viscous at ambient temperature such that the material can be melted and applied hot to the substrate.
During the washing process, the zone containing the quaternary ammonium cationic surfactants may break into smaller pieces. On the one hand, some of these pieces are subsequently released from the surface of the substrate and are carried away by the washing liquor. On the other hand, pieces that remained on the surface of substrate during the washing process may be transferred en bloc to the cloths in the subsequent drying process in the clothes dryer, leading to spotting.
Therefore in spite of the prior art developments, there is still a need for a laundry article comprising a water-insoluble substrate coated with a detergent composition and a fabric conditioning composition that shows little to no spotting of clothing.